Recently, it has been appreciated that several types of K channels play a crucial role in the regulation of vascular smooth muscle contraction and therefore, peripheral vascular resistance and blood pressure. We have cloned a novel gene from rabbit that encodes a cGMP-gated K channel (Kcn). Since Kcn is expressed in vascular tissues and since it is directly activated by cGMP it is likely that it participates in the regulation of arterial tone. An exciting possibility is that the abnormal regulation of Kcn may contribute directly to the pathogenesis some cases of hypertension. For these reasons, we believe that the detailed study of the regulation of Kcn gene expression is very worthwhile. In preliminary studies, we have partially characterized a 1.1 kb 5' flanking fragment for the Kcn gene. That fragment is transcriptionally active and gene expression is regulated by cAMP, steroid hormones and phorbol esters. Furthermore, the fragment also contains a 5' enhancer. We have also identified and partially characterized two isoforms (distinct genes) of the Kcn gene. Based on the above findings, we propose to perform a detailed characterization of the promoter and other regulatory regions and to examine the molecular basis of cell specific expression of the Kcn genes including a search for additional control elements and an examination of DNA-Protein interaction. The other major part of the project is aimed at testing the hypothesis that Kcn-like genes play a role in the pathogenesis of hypertension. For these studies, the human counterpart for the Kcn genes will be isolated by screening human cosmid libraries. We will search for informative genetic markers in the Kcn gene family. These markers will allow us to perform linkage analysis with these genes in human hypertension. Linkage analysis will be carried out with Kcn genes in African Americans and Caucasian hypertensive sibling pairs. If linkage is found, mutations in the Kcn genes will be searched for by single strand conformational polymorphism (SSCP) and RNAse protection assay (RPA). The functional consequence of any mutations that are found will be determined by expression of the mutated gene in Xenopus oocytes. In conclusion, we believe that these studies may lead to a greater understanding of the process of vasoregulation, to the discovery of genes causing hypertension and to the development of new, potent antihypertensive drugs.